iOS- 利用AFNetworking3.0+（最新AFN) - 实现文件断点下载

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@interface ViewController ()

{

    // 下载句柄

    NSURLSessionDownloadTask *_downloadTask;

}

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.h文件

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

// 下载文件显示

@property (weak, nonatomic) IBOutlet UIImageView *imageView;

// 下载进度条显示

@property (weak, nonatomic) IBOutlet UIProgressView *progressView;

@end

.m文件

@interface ViewController ()

{

    // 下载句柄

    NSURLSessionDownloadTask *_downloadTask;

}

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- (void)downFileFromServer{

    //远程地址

    NSURL *URL = [NSURL URLWithString:@"http://www.baidu.com/img/bdlogo.png"];

    //默认配置

    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];

    //AFN3.0+基于封住URLSession的句柄

    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

    //请求

    NSURLRequest *request = [NSURLRequest requestWithURL:URL];

    //下载Task操作

    _downloadTask = [manager downloadTaskWithRequest:request progress:^(NSProgress * _Nonnull downloadProgress) {

        // @property int64_t totalUnitCount;     需要下载文件的总大小

        // @property int64_t completedUnitCount; 当前已经下载的大小

        // 给Progress添加监听 KVO

        NSLog(@"%f",1.0 * downloadProgress.completedUnitCount / downloadProgress.totalUnitCount);

        // 回到主队列刷新UI

        dispatch_async(dispatch_get_main_queue(), ^{

        // 设置进度条的百分比

            self.progressView.progress = 1.0 * downloadProgress.completedUnitCount / downloadProgress.totalUnitCount;

        });

    } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {

        //- block的返回值, 要求返回一个URL, 返回的这个URL就是文件的位置的路径

        NSString *cachesPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];

        NSString *path = [cachesPath stringByAppendingPathComponent:response.suggestedFilename];

        return [NSURL fileURLWithPath:path];

    } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {

        //设置下载完成操作

        // filePath就是你下载文件的位置，你可以解压，也可以直接拿来使用

        NSString *imgFilePath = [filePath path];// 将NSURL转成NSString

        UIImage *img = [UIImage imageWithContentsOfFile:imgFilePath];

        self.imageView.image = img;

    }];

}

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- (IBAction)stopDownloadBtnClick:(id)sender {

    //暂停下载

    [_downloadTask suspend];

}

- (IBAction)startDownloadBtnClick:(id)sender {

    //开始下载

    [_downloadTask resume];

}

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- (void)viewDidLoad {

    [super viewDidLoad];

    //网络监控句柄

    AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];

    //要监控网络连接状态，必须要先调用单例的startMonitoring方法

    [manager startMonitoring];

    [manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {

        //status:

        //AFNetworkReachabilityStatusUnknown          = -1,  未知

        //AFNetworkReachabilityStatusNotReachable     = 0,   未连接

        //AFNetworkReachabilityStatusReachableViaWWAN = 1,   3G

        //AFNetworkReachabilityStatusReachableViaWiFi = 2,   无线连接

        NSLog(@"%d", status);

    }];

    //准备从远程下载文件. -> 请点击下面开始按钮启动下载任务

    [self downFileFromServer];

}